News tagged with melanin

Much of the damage that ultraviolet radiation (UV) does to skin occurs hours after sun exposure, a team of Yale-led researchers concluded in a study that was published online Feb. 19 by the journal Science.

A new research report published in the January 2015 issue of the FASEB Journal helps explain what goes wrong to when someone gets skin cancer and the relationship between changing skin pigment and the cancer itself. In particular, ...

(Medical Xpress)—A new study by University of Kentucky researchers shows how a genetic defect in a specific hormonal pathway may make people more susceptible to developing melanoma, the deadliest type of skin cancer.

(Medical Xpress)—Itchy, painful rashes—such as those that occur with psoriasis—are uncomfortable, but at least they fade when the flare-up subsides. Mostly. Evidence often remains in the form of dark, discolored areas ...

When Homo sapiens left Africa and had to adapt to less sunny climates, there was a mutation in one of the genes responsible for regulating the synthesis of melanin, the MC1R gene, which involved a discoloration of the skin. ...

Researchers have identified a genomic variant strongly associated with sensitivity to the sun, brown hair, blue eyes – and freckles. In the study of Icelanders the researchers uncovered an intricate pathway involving the ...

In a retrospective study, Saint Louis University researchers have found that patients with melanoma brain metastases can be treated with large doses of interleukin-2 (HD IL-2), a therapy that triggers the body's own immune ...

(Medical Xpress)—Motile cilia are present on the surface of many types of cells. When they are not working properly, respiratory problems, various sensory deficits, and occasionally, even a reversal of placement of the ...

If a tumour has spread through the lymph nodes, the decision is often taken to exercise caution and remove extra tissue, to prevent it from spreading further. This often involves the removal of healthy lymph nodes. Photoacoustic ...

Melanin

Melanin i/ˈmɛlənɪn/ (Greek: μέλας, black) is a pigment that is ubiquitous in nature, being found in most organisms (spiders are one of the few groups in which it has not been detected). In animals melanin pigments are derivatives of the amino acid tyrosine. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms. All melanins can be considered as derivatives of polyacetylene, since they rely on a polyconiugate structure. Another common form of melanin is pheomelanin, a red-brown polymer of benzothiazine units largely responsible for red hair and freckles. The presence of melanin in the archaea and bacteria kingdoms is an issue of ongoing debate among researchers in the field.

The increased production of melanin in human skin is called melanogenesis. Production of melanin is stimulated by DNA damage induced by UVB-radiation, and it leads to a delayed development of a tan. This melanogenesis-based tan takes more time to develop, but it is long-lasting.

The photochemical properties of melanin make it an excellent photoprotectant. It absorbs harmful UV-radiation (ultraviolet) and transforms the energy into harmless heat through a process called "ultrafast internal conversion". This property enables melanin to dissipate more than 99.9% of the absorbed UV radiation as heat (see photoprotection). This prevents the indirect DNA damage that is responsible for the formation of malignant melanoma and other skin cancers.